bb.setRotate( degrees );
Here is a program that draws a simple star. The star is made of three lines intersecting at the center.
The program draws one horizontal line,
then draws another horizontal line rotated by 60 degrees,
and the draws a third horizontal line rotated by -60 degrees.
import javafx.application.*;
import javafx.stage.*;
import javafx.scene.*;
import javafx.scene.shape.*;
import javafx.scene.paint.*;
public class OneStar extends Application
{
void addStar( Group root, Color color, double centerX, double centerY, double size )
{
double startX, endX, startY, endY;
// horizontal line
startX = centerX - size/2;
endX = centerX + size/2;
Line line = new Line( startX, centerY, endX, centerY );
line.setStrokeWidth( 2.0 );
line.setStroke( color );
root.getChildren().add( line );
// upward slanting line
startX = centerX - size/2;
endX = centerX + size/2;
line = new Line( startX, centerY, endX, centerY );
line.setRotate( -60.0 );
line.setStrokeWidth( 2.0 );
line.setStroke( color );
root.getChildren().add( line );
// downward slanting line
startX = centerX - size/2;
endX = centerX + size/2;
line = new Line( startX, centerY, endX, centerY );
line.setRotate( +60.0 );
line.setStrokeWidth( 2.0 );
line.setStroke( color );
root.getChildren().add( line );
}
public void start(Stage stage)
{
double sceneWidth=400, sceneHeight= 300;
Group root = new Group( );
addStar( root, Color.BLUE, sceneWidth/2, sceneHeight/2, sceneWidth*0.6 );
Scene scene = new Scene(root, sceneWidth, sceneHeight, Color.SNOW );
stage.setTitle("One Star");
stage.setScene(scene);
stage.show();
}
}
What do you predict the following start() draws?
Notice the role of size.
public void start(Stage stage)
{
double sceneWidth=400, sceneHeight= 300;
Group root = new Group( );
double size=sceneWidth*0.3;
addStar( root, Color.BLUE, sceneWidth/2+size, sceneHeight/2, size );
Scene scene = new Scene(root, sceneWidth, sceneHeight, Color.SNOW );
stage.setTitle("Tiny Star");
stage.setScene(scene);
stage.show();
}
}